Matching colors is always a challenge and sometimes frustrating, particularly when trying to recreate a model from a color photograph. There are several factors which make this a rather inexact science: age of the photo, lighting conditions, fading of the paint on the tank, and so on.
When you get right down to it, it doesn’t matter as much as you may think because the colors used in real life varied so much. The actual shade depended on the method of application and the amount and method of dilution. Field applied camo colors were supplied in tins in a paste form (similar to shoe polish) to be diluted with gasoline or water. Depending on time and available supplies it was sprayed or brushed on (sometimes with mops or brooms).
Also in August 1944, the Olive Green and Red Brown changed (new specs): The OG was a darker shade, and the RB lighter, more reddish.
For field application, Panzer units were supplied in 2 and 20 kg drums in a paste form. This was to be thinned with petrol or water and applied with spray guns or brushes. Depending on the amount and method of dilution as well as the method of application and who did the painting the colors could vary wildly. In the concentrated form the red-brown looked purplish! One author, when commenting on the odd color schemes of WWI German aircraft, thought Germans have a strange sense of camo schemes as he recalled seeing a salmon and maroon colored Tiger tank in the Ardennes.
Also the Germans had changed the color specification during the war: To Feb 1943
>Dark Gray (RAL 7207) “Panzer Gray” >(for Africa)
>Desert Brown (RAL 8020) Deep pinkish tan
>Late 1942 (officially Feb 1943)
>Dark Yellow (RAL 8000) Yellow-brown, with gray-green cast
>Olive Green (RAL 7008) grayed low contrast olive green
>Red Brown (RAL 8017) reddish brown
>Dark Yellow (RAL 8000)
>Olive Green (RAL 6003)
>Red Brown (RAL 8012) darker than RAL 7008; lighter, more red than RAL 8017
From Feb 1943 to November 1944 Dark Yellow was used as the base (vehicles painted this color at the factory). From Aug 1944 the base color was the RAL 6003 Olive Green. The older colors continued to be used as long as stock was available. (RAL is the Reichs Ministry of Armaments catalog number).
Source: Panzerkampfwagen Tiger by Uwe Feist and Bruce Culver, Ryton Publications 1992.